From an old friend, this man has now become Elon Musk’s sworn enemy.

Over the past year, the rivalry between Silicon Valley titans Sam Altman and Elon Musk has escalated into personal attacks, social media spats, and lawsuits.

Musk has called his rival “Scam Altman” and “Swindly Sam.” Altman has said Musk “cannot be a happy person” and that his “whole life is driven by insecurity.” This week, after Musk announced he would sue Apple for allegedly promoting Altman’s OpenAI in the App Store over his own xAI startup, Altman accused Musk of manipulating X to “serve himself and his companies.” Musk responded by calling Altman a liar.

The two co-founded OpenAI as a nonprofit in 2015, but Musk stepped down from the board three years later after a failed acquisition attempt. When OpenAI launched ChatGPT in late 2022 to great fanfare, Musk founded xAI in March 2023, touting it as an “anti-woke solution.” Last year, Musk sued Altman to stop his former friend from turning OpenAI into a for-profit company. Altman countersued, saying Musk had “relentlessly” tried to sabotage OpenAI.

But the competition between OpenAI and xAI is now just one front in a larger battle between Altman and Musk, with Altman making a number of moves—both through OpenAI and through his vast personal investment portfolio—to develop products and technologies that directly target Musk’s businesses.

Altman is backing a new brain-computer interface startup called Merge Labs, which is directly competing with Musk’s Neuralink, according to the Financial Times. Altman co-founded the company, which is currently raising capital at a valuation of $850 million. (Interestingly, Altman was also a small investor in Neuralink.) Neuralink, which Musk co-founded in 2016, is currently valued at around $9 billion, with Musk as its largest individual shareholder.

In parallel, Altman is also positioning OpenAI to compete directly with X – Musk’s social network (formerly Twitter). According to The Verge, OpenAI is building an “X-like” social platform that could pose a major threat to X. Currently, X has about 600 million monthly users (according to Statista), while OpenAI claims ChatGPT has up to 700 million weekly users.

Altman didn’t stop there, but he also took aim at Tesla. Tesla’s sales fell 13.5% in the second quarter of 2025 compared to the same period last year, prompting Musk to turn to self-driving taxis as a new growth driver. He told CNBC in May that “by the end of next year, there will be hundreds of thousands, if not over a million, self-driving Teslas in the U.S.” But there’s no evidence that Tesla has been approved for full self-driving yet.

Meanwhile, in June, OpenAI announced a partnership with Applied Intuition (a self-driving software company valued at $15 billion) to “advance the next generation of AI-powered car experiences globally.” Altman then asserted that OpenAI had made a big step forward in self-driving technology, while also taking a swipe at Tesla: “We have new technology that can make self-driving cars better than any current approach,” Altman said on his brother’s podcast.

Altman also invested in Longshot Space, a company that dreams of competing with Musk’s SpaceX. He also invested in Glydways, another self-driving car startup that could one day rival Tesla’s robot taxis.

FROM FRIEND TO ENEMY

Musk, 54, and Altman, 40, weren’t always rivals. They met in the early 2010s, when Altman was president of startup incubator Y Combinator and Musk was focused on expanding SpaceX and Tesla.

The two connected over their shared concerns about the dangers of artificial intelligence, and co-founded OpenAI in 2015 with the goal of developing responsible AI. Musk has been the organization’s largest donor, contributing $44 million in 2016–2017.

Musk, however, left OpenAI’s board in 2018 after what was widely seen as a failed attempt to merge the organization with Tesla. The two appear to have remained on good terms, though. In 2019, when Tesla was struggling, Altman defended the company, saying that “betting against Elon has always been a mistake in history.”

When ChatGPT went public in November 2022, Musk also praised the chatbot as “so creepy and brilliant” and criticized the New York Times for not reporting it fully.

But the relationship began to fray in 2023, as Musk prepared for xAI. In February 2023, Musk posted a meme suggesting that ChatGPT had usurped the media and become “the captain of propaganda.” In March, he worried that Microsoft had “exclusive access to the entire OpenAI source code” after investing $13 billion.

The two sides remained friendly, however, even joking and philosophizing with each other on social media. But by late 2023, Musk had begun publicly mocking ChatGPT, calling it “annoying” and using xAI’s Grok chatbot to make sarcastic remarks.

The conflict escalated in early 2024, when Musk made a $97.4 billion offer to buy OpenAI’s assets (which the company did not sell), and then sued OpenAI, Altman, and co-founder Greg Brockman in California. Musk later withdrew the lawsuit but filed a similar lawsuit in federal court. In April of this year, OpenAI countersued, accusing Musk of a “year-long campaign of harassment” aimed at undermining OpenAI. The court dismissed some of Musk’s claims and allowed OpenAI to continue its counterclaims. The trial is scheduled for next year.

As the feud between the two deepens, many in Silicon Valley are watching with amusement. Billionaire investor Vinod Khosla—who has warned about the dangers of AI—thinks that the competition is ultimately good for the ecosystem: “The more competition, the better,” he told Forbes in an email.

But convincing Musk or Altman to believe that would be no easy task.